Shrinkproofing of animal fibers



Oct 8, 1968 w THORSEN ET AL 3,404,942

SHRINKPROOFING OF ANIMAL FIBERS Filed Aug. 18, 1965 HEAT EXCHANGE ROLL OF FABRIC FLUID TO BE TREATED FIGI W.J. THORSEN 8 ROBERT Y. KODANI NENTORS BY 'Illi ATTORNEYS Uited States Patent C A non-exclusive, irrevocable, royalty-free license in the 'avention herein described, throughout the world for all purposes of the United States Government, with the power to grant sublicenses for such purposes, is hereby granted to the Government of the United States of America.

This invention relates to and has among its objects the provision of novel process and apparatus for shrinkproofing proteinous animal fibers, e.g., wool, mohair, and the like. Further objects of the invention will be evident from the following description wherein parts and percentages are by weight unless otherwise specified.

The annexed drawing illustrates a form of apparatus for applying the process of the invention. FIGURE 1 is a side view, partly in cross-section. FIGURE 2 is a partial view, on an enlarged scale, taken in the direction as indicated by arrows 2, 2 in PEG. 1.

As a general proposition, the treatment of wool with ozone has been described heretofore and has "been suggested as a means of improving the shrinkage properties of the textile. Various investigators have explored the situation and have advocated different techniques for accomplishing their desired ends. A typical procedure is that described in British Patent No. 242,027, Nov. 5, 1925. in this process, wool is soaked in 5% ammonia solution for a few minutes, hydro-extracted (centrifuged) to remove excess liquid, then placed while damp in a chamber wherein it is exposed to air containing ozone in a concentration of about one part per 1000. The process is exceedingly slow as evidenced by the fact that the patentees suggest removing samples of the wool at intervals of a few hours to test them for acidity. (If acid, the wool is again soaked in ammonia solution prior to further ozone treatment.) The procedure of the British patent, termed the Zair process, was further investigated by Brown (iournal of the Society of Dyers and Colourists, Vol. 44, pp. 230-233, 1928) who illustrates the long duration of the process, i.e., 5 to 20 hours. in addition to requiring long processing times, the various prior procedures have involved such disadvantages as erratic and non-uniform results, decrease in abrasion resistance of the treated wool, and even loss of material during processing by dissolving of a portion of the fibers. As a net result, the ozone treatment of wool has not met with commercial acceptance.

More recently, one of the present inventors, Walter J. Thorsen, has shown in US. Patent No. 3,149,906 that much faster shrink-proofing of wool is obtained Where a stream of ozone and steam is blown through the textile under treatment. For example, it is shown in this patent that wool can be rendered shrinkproof in a processing time of 1 to 10 minutes.

In the treatment of textiles it is a universal desideratum that the material be treated continuously rather than in batches. in attempts to adapt the process of the aforesaid Thorsen process to continuous operation, serious difficulties were encountered. The main problem was that it proved diflicult and expensive to force the gas through the fabric as it moved continuously through the system. Fabrics offer a considerable resistance to gas flow and the equipment required to achieve a satisfactory gas flow rate through the fabric is both elaborate and costly. Also, with such a system there is considerable wastage of ozone as only a fraction of available ozone in the stream can react with the wool in the time it takes the stream to pass through the fabric.

It is, accordingly, a prime object of the present invention to provide a process by which the aforesaid problems are obviated. Basically, the process of the invention involves the following procedure: The fabric is moved over a heated surface and concomitantly a gas stream containing ozone is passed over the surface of the fabric. In the process of the invention, no attempt is made to force the through the fabric. Instead, the gas is moved parallel to the fabric surface. Surprisingly, we have found that this parallel movement of the gas is efiective, indeed, more effective than where the gas is forced through the fabric. One unusual result of the process of the invention is that the parallel gas flow causes uniform modification of the wool. For example, the underside of the fabric which is not directly exposed to the gas is modified to the same extent as the top surface which is in direct contact with the gas.

Another advantage of the process of the invention is that it can be carried out with equipment which is simple and inexpensive.

The process of the invention involves efiicient utilization of ozone in that the gas can react with the fabric until exhausted, i.e., no unreacted ozone is discharged from the equipment.

A further item is that fabrics are rendered shrinkproof in a very short period3() to 60 seconds-so that the process is adapted for continuous treatment of long lengths of textiles. The short time required for the treatment has the added advantage that degradation eifects on the h ers are eliminated.

the process of the invention, the dyeing properties of the fabric are not substantially altered. This has the dva .age that the products can be dyed following convention. formulations and schedules. Accordingly, the procthe inve tion can be applied to a conventional textile processi; line without interference with the dyeing procedure normally employed in the plant.

The practice of the invention is further described as follows, having reference to the annexed drawing. The illustrated apparatus includes a reaction chamber 1 formed by top plate 2, bottom plate 3, and side plates 4. These elements are dimensioned so that reaction chamber 1 has a hei of about inch, a width matching the width of the fabric being treated, and a length of about 3 to 20 feet, or more. (In the alternative, several reaction chambers maybe provided along the len th of the fabric to provide adequate area under treatment at any One time.) The left hand end of reaction chamber 1 is open to the atmosphere as evident in FIGURE 1; the opposite end is closed by dam 5 which is spaced from bottom plate 3 by a distance large enough to permit the passage of fabric thereunder.

Abutting against bottom plate 3 is heat-exchange unit 5 provided with tube 7 for circulation of a heat exchange fluid therethrough to maintain plate 3 and the fabric restthereon at a desired temperature. in order to obtain a rapid shrii proofing effect it is essential to keep the fabric hot. Usually, the system is operated under such conditions that plate 3 is maintained at about 80170 C., preferably 100-130 C. Upper plate 2 may be provided with a similar tubulated heat exchanger 8, as shown in the drawing. However, generally heating is adequate when applied from the surface contacting the fabric and this upper heat exchanger unit may be omitted.

For production of ozone there is provided a conventional ozone generator (not illustrated). Generally, the effluent from the generator is a gas containing about 4 to 6% ozone, the remainder being usually oxygen, a mixture of oxygen and nitrogen, or other inert carrier gas. The gas stream from the generator is introduced into reaction chamber 1 via manifold 9 which is provided with a series of bores cooperating with corresponding bores 10 in upper plate 2. In this way the gas stream is introduced uniformly over the width of the fabric to be treated. Within reaction chamber 1 the gas flows toward the open end (lefthand end in FIG. 1). In operation, essentially all the introduced ozone reacts with the fabric and the gas issuing out of the open end is mainly the carrier gas (usually oxygen or oxygen and nitrogen).

The various parts of the device which come into contact with ozone-e.g., plates 2, 3, 4 etc.are generally made of ozone-resistant material such as aluminum.

In operation, fabric is dampened and hydro-extracted or pressed to about 30-40% moisture. This damp fabric, designated as 11 in FIG. 1, is drawn by driven rolls 12 and 13 through reaction chamber 1 at a speed such that the fabric resides in the chamber for a period long enough to attain the desired shrinkproofing effect but not long enough to cause significant degradation of the fabric. Generally, this residence time is about 30 to 60 seconds. Within reaction chamber 1 the fabric is concomitantly heated and exposed to the ozone-containing gas stream, and thereby rendered shrinkproof. The treated fabric is designated as 11a in the drawing.

A particularly critical aspect of the invention is the way in which the gas contacts the fabric. Thus the gas flow is positively confined to a region close to the fabric surface and parallel thereto. This control of the gas flow path is effected in the illustrated modification by the arrangement of plates 2, 3, and 4. Particularly important in this regard is the closeness of plates 2 and 3 which hold the gas close to the fabric. It has been found that when the gas flow is restricted as aforesaid, the shrinkproofing effect isestablished very rapidly. The reason for this action is not completely understood but it is believed that such restriction of the gas flow causes a turbulent effect that impels individual ozone molecules into and through the fabric and so causes the desired modification rapidly and uniformly. The situation is thus completely different from previously advocated systems wherein the ozone is contained in a large chamber and the fabric threaded through the chamber. In such case the conditions are relatively static and no turbulent effect is present to impel the ozone molecules into the mass of the fabric. As a consequence, such procedures are very slow requiring hours to establish the desired shrinkproofing effect. T sum up the situation, by positively directing the gas flow in a region close to and parallel to the fabric surface, we attain a dynamic condition which yields results far superior to anything achieved by the prior techniques.

In the preferred modification, as illustrated in the drawing, a countercurrent system is employed. Thus. the fabric moves in one direction (left to right in FIG. 1) while the gas stream moves in the opposite direction (right to left in FIG. 1). Although a concurrent flow system can be used, countercurrent flow gives superior results, e.g., a greater degree of shrinkproofing for a given time of treatment. Such superior results are achieved because in the countercurrent system a proper chemical driving force is maintained throughout the path of travel of the fabric. Thus, as the fabric passes from left to right its degree of modification increases but at the same time the amount 4 of ozone in the gas stream likewise is increasing. The result is that a driving force is maintained which causes further modification of the fabric as it progresses through the system. Such driving force is not present in a con cur-rent system. Thus, in such a system the unmodified fabric meets the highest concentration of ozone and as the modified fabric passes through the system, the gas stream in contact therewith has a decreased concentration of ozone which. means that there is no driving force tending to further modify the partly-modified fabric.

The process of the invention is applicable to proteinous animal fibers in general. Typical of such fibers are wool, mohair, camel hair, alpaca, silk, fur, etc. For continuous operation the process is preferably applied to fabrics made of such fibers. The fabrics may be of woven or knitted construction or simply compacted webs of interlaced fibers.

Example The invention is further demonstrated by the following illustrative example:

in the various runs, wool fabric (worsted-flannel) was continuously treated in an apparatus as shown in the drawing. The reaction chamber had a height of @1 inch, a width of 1 foot, and a length of 4 feet. The plate temperature was held at 100 C. The gas stream, applied at 2 cu. ft./min., was ozone-oxygen with an ozone concentration of ing/liter. Prior to treatment, the fabric was immersed in water, then hydro-extracted to a moisture content of 30-40%. Runs at different speeds were made to vary the residence time of the fabric in the reaction chamber.

Following the treatment with ozone, samples of the treated and untreated fabric were tested for felting shinkage by measuring the area of the samples before and after washing. The washing was done in a household-type automatic washer, using a -minute suds time at 38 C., a 3-pound ballast load, and 0.1% of alkaline-built non-sudsing detergent. The same washing treatment was then repeated for a total of 4 times. The results are tabulated below:

Residence Area shrinkage, percent time in (cumulative) Run reaction chamber, After After After After sec. 1st 2nd 3rd 4th wash wash wash wash l Untreated control.

Samples of the treated and untreated fabric were also subjected to various other physical tests to compare their properties. The results are tabulated below. The abbreviations W and F refer to warp and fill, respectively.

Treated fabric (Run 3: 60 sec. residence time) 387(W), 527(F) 175(W), 177(F) Test Untreated fabric Resistance to abrasion, cycles. 504(W), 529(13) Flexural rigidity, mg./cm 117(W), (F) Color tests Reflectance (R value), per- (53 con Yellowncss index (0 value) 13. 7 13. 9 Tear strength, grams 1,165(W), 1,171(F) 941(W), 1,0050") Wrinkle recovery 6 145(W), 145(F) 129(W), (F) Breaking strength, lbs 19.2(W), 18.6(F) 20.4(W), 22.503)

Having thus described the invention, what is claimed is: 1. A process for shrink-proofing a fabric of protcinous animal fibers which comprises, applying heat at a tem- 5 6 peraturc in the range 80170 C. to one side of the fabric, References Cited concomitantly passing a gas stream containing ozone over the oposite side of the fabric, and positively confining the FOREIGN PATENTS passage of said gas to a path adjacent and parallel to said 72 ,771 4/1 55 Great Brit in.

opposite side.

2. The process of claim 1 wherein the fabric of pro- NORMAN TORCHIN Primal); Examine,"

teinaceous animal fibers is moistened prior to the appli- CANNON, Assistant Examinercation of heat thereto. 

1. A PROCESS FOR SHRINK-PROOFING A FABRIC OF PROTEINOUS ANIMAL FIBERS WHICH COMPRISES, APPLYING HEAT AT A TEMPERATURE IN THE RANGE 80-170*C. TO ONE SIDE OF THE FABRIC, CONCOMITANTLY PASSING A GAS STREAM CONTAINING OZONE OVER THE OPPOSITE SIDE OF THE FABRIC, AND POSITIVELY CONFINING THE PASSAGE OF SAID GAS TO A PATH ADJACENT AND PARALLEL TO SAID OPPOSITE SIDE. 